Various inventions relating to pumps have been proposed. One of examples of such inventions has been disclosed as follows: “reducing the gap between a stator core and a magnet of a pump so as to improve motor efficiency and capability of cooling coils and a control circuit” (see, for example, Patent Literature 1). In the pump described in Patent Literature 1, the gap between the stator core and the magnet is reduced by reducing the thickness of a separation plate. The reduction of the thickness of the separation plate is achieved by inserting the coils, the stator core, the control circuit, and the separation plate, and surrounding the resultant structure with molded resin. In the pump described in Patent Literature 1, spaces around the coils and the control circuit, which produce heat, and the separation plate are filled without a gap with the molded resin having a good thermal conductivity. Thus, the thermal conductivity is improved, and accordingly, the capability of cooling can be improved.
Also, a technique, in which “a molded stator and a pump unit can be firmly attached to each other”, has been disclosed (see, for example, Patent Literature 2). The pump described in Patent Literature 2 includes “[A] molded stator that includes a stator, which includes coils and a board. The coils are wound around a plurality of teeth, which are provided with insulating portions, of a stator core. An electrical component is mounted on the board and a lead cable guiding component, through which a lead cable is drawn out, is attached to the board, which is attached to the stator. The molded stator also includes a pilot hole component that has a plurality of leg portions having pilot holes. The stator and the pilot hole component are attached to each other to form a stator assembly, around which a resin for molding is molded, and the pilot holes of the leg portions of the pilot hole component is exposed in one end plane in the axial direction. The pump also includes the pump unit that includes a casing having an inlet and an outlet for water, a cup-shaped bulkhead component that has a flange portion and a cup-shaped bulkhead portion. The rotor is attached in the cup-shaped bulkhead portion such that a shaft, engaged with the rotor, is not rotatable. A rotor portion and an impeller are provided to the rotor. The cup-shaped bulkhead component is attached to the molded stator to form the pump unit having a plurality of screw holes near an outer circumferential portion thereof. The pump also includes a plurality of self-tapping screws. In the pump, the pump unit and the molded stator are attached to each other by screwing the self-tapping screws into the exposed pilot holes of the molded stator through the screw holes of the pump unit”.